Clear protective overcoat for a printed medium

ABSTRACT

A transparent, protective overcoat for a printed medium achieved with a thermal transfer material on a carrier ribbon that is heated and pressed to transfer a segment of thermal transfer material from the carrier ribbon onto the printable surface of a medium.

FIELD OF INVENTION

[0001] The present invention, relates to a clear protective overcoat fora printed medium, achieved with a thermal transfer material and acarrier ribbon forming a donor web which is subjected to heat andpressure to transfer a segment of thermal transfer material from thedonor web onto the printed area on the printable surface of a medium.

BACKGROUND OF INVENTION

[0002] Digital photography and imaging provide cost-effectivealternatives for capturing images, but known methods of producingdurable, hardcopy prints of digitally printed areas are at least asexpensive as traditional photographic methods. Further, with increasinguse of various printing and imaging technologies in the publishingindustry as well as in the home, protecting imaged or printed documentsagainst abrasion, water alcohol, other liquid spills, ink smear, fading,blocking or other image-degradation processes and effects has become animportant consideration. Such protection is particularly desirable forprinted or imaged documents produced with water-based (water-soluble) orother liquid inks, as well as documents printed or imaged with toner.These are commonly used in ink-jet printing, offset printing,electrophotography and the like.

[0003] Photography provides an easy and reliable way to permanentlycapture images for a variety of uses. While photographs provide durableimages, they are prone to scratches, have poor resistance to light andultraviolet radiation (which causes photographic images to fade overtime), and degrade when exposed to water, other liquids or to vapors ofsuch liquids. Traditional photography uses harsh and expensivechemicals, requires silver recovery, and involves a process requiringseveral intermediate steps of handling negatives. While photographicprocesses can be automated, such automatic processing machines areexpensive and bulky and do not eliminate the inherent problems ofchemical exposure and handling negatives. Additionally, producing largeprints (larger than the traditional 3-by-5 inch or 4-by-6 inch prints)can be quite expensive.

[0004] Hot and cold laminates are the most common methods used toprotect printed areas. However, laminates tend to be expensive,typically costing 6 to 80 cents per square foot for materials. Thelabor-intensive nature of producing durable prints via lamination alsoincreases the cost of such prints. Laminates may be applied on one orboth surfaces of the print. One-sided lamination may lead to excessivecurling of the final print, whereas two-sided application can be veryexpensive in terms of material and labor costs and may excessivelyincrease the thickness of the final print. Adhesives used for coldlaminates may be tacky at room temperature, leaving a sticky residue atthe edges of the prints. Additionally, binders used in creating coldlaminates are typically water-based, which means the print maydelaminate if exposed to excessive water or other liquid. Laminates arealso susceptible to trapped air pockets, which are viewed as imagedefects. Most importantly, care must be taken to ensure that thelaminates are accurately aligned to the media, and such alignment isespecially critical for a continuous web laminate. These are just someof the deficiencies of traditional laminates.

[0005] Liquid overcoats are also commonly used to protect photographicprints and are becoming more popular as protective coatings for inkjetprinted areas. Typical systems for applying these overcoats rely onroller coating or gravure type systems to dispense, gauge, and apply thecoating. Smaller systems typically apply the overcoat off-line, ratherthan being an integral part of a single printing and coating unit.Larger systems used by the printing industry are in-line, but requireextensive monitoring. Both systems require significant manual cleaningor intervention to maintain the components that contact the liquid.

[0006] Liquid overcoats tend to be slightly less expensive thanlaminates (6-18 cents per square foot). However, because currentlyavailable systems must be cleaned frequently and regularly monitored,these methods of using liquid overcoats are just as labor-intensive asthe lamination methods, if not more labor-intensive.

[0007] Additionally, many of the overcoat formulations have residualodors before and/or after application, and some people find these odorsoffensive or even harmful.

[0008] Ultraviolet (UV) light curable liquid overcoats are alsoavailable, such as the overcoats commonly used to protect magazinecovers. In such a UV-curable system, the liquid is first applied to thesurface of the print and then cured to yield a solid, durable,protective coating. Because these liquids are widely used in largevolumes for the magazine industry, their cost tends to be significantlylower than most other overcoat options. However, the systems used toapply such UV-curable overcoats tend to be more complicated and costlythan other liquid overcoat systems, due to the multi-step applicationand cure process. Additionally, many of the overcoat formulations havestrong odors, some of which are harmful or offensive to people.Furthermore, there are potential safety problems associated with thehandling of the potentially hazardous liquids used in this process.

[0009] Malhotra (U.S. Pat. No. 5,612,777 assigned to Xerox), Tutt &Tunney (U.S. Pat. No. 5,847,738 assigned to Eastman Kodak Co.) and Tyagiet al. (U.S. Pat. No. 5,783,348 assigned to Eastman Kodak Co.) disclosemethods of applying a clear, scratch-resistant, lightfast, toner coatingonto printed areas. Malhotra describes photocopied color images createdby first, depositing color toner on a charge retentive surface; second,depositing a clear polymer toner material onto the charge retentivesurface; and third, transferring and fusing the color toner and clearpolymer toner material onto a substrate. Tutt & Tunney describe aprocess of depositing and fusing a clear polymer toner on inkjet printedareas. Tyagi et al. describes a similar process for coating clear tonerover silver halide printed areas.

[0010] Similar electrostatic coating methods are also commonly used inthe commercial painting industry to powder coat products, parts, orassemblies. One powder coating method charges a powdered paint using anair gun outfitted with an electrode before spraying the charged paintonto an electrically grounded object. Alternatively, an electricallygrounded object may be immersed in a charged, fluidized bed of paintparticles (typically referred to as“fluidized bed powder coating”).

[0011] Another Malhotra patent (U.S. Pat. No. 5,906,905 assigned toXerox) discloses a method of creating photographic quality prints usingimaging such as xerography or ink jet by, first, reverse reading tonerprinted areas on a transparent substrate and then adhering thetransparent substrate to a coated backing sheet, coated with a polymericlightfastness material.

[0012] The application of thermal film material on a thermally printedsubstrate is also disclosed. Nagashima (U.S. Pat. No. 4,738,555 assignedto Toshiba) discloses the use of a thermal printhead to thermallytransfer a transparent protective layer of wax, vinyl chloride, vinylacetate, acrylic resin, styrene or epoxy onto the thermally printedmedium substrate.

[0013] Tang et al. (U.S. Pat. No. 5,555,011 assigned to Eastman Kodak)discloses a means to ensure that a thermal film that is being applied toa thermally printed surface has a clean break at the edge of thetransfer. It describes a thermal film transfer method having a transportsystem which moves a dye-donor web and a receiver medium (i) in aforward direction along their respective paths past a thermal head, sothat heat from the thermal head causes an area of the thermal filmmaterial coating between leading and trailing edges to transfer from thedye-donor web to the receiver medium and (ii) in a reverse directionalong their respective paths such that the area of the thermal filmmaterial which is transferred to the receiver medium breaks cleanly atthe trailing edge from a non-transferred area of the thermal filmmaterial that remains on the dye-donor web as the web support separatesfrom the medium.

[0014] Abe et al. (U.S. Pat. No. 5,954,906 assigned to Canon) disclosesa method for protecting and covering a printed material on a substratewith a pressure-sensitive protective covering material with at least (a)a first flexible substrate, (b) an adhesive layer, (c) a solid resinlayer, and (d) a second flexible substrate, stacked in this order.

[0015] The packaging, printing, and decorating industry uses coloredribbons, known as thermal transfer foils, hot stamping foils, rollfoils, and transfer printing foils, for marking or decorating. Thismarket uses solid fill colored ribbons or uniquely patterned ribbons toemboss lettering, patterns, barcodes, or insignias on wood, paper,leather, plastic, fabric, or metal parts. Examples include holograms oncredit cards, metalized insignias on baseball cards, corporate logos onbusiness cards, or colored or metalized designs on greeting cards. Thehot stamp foiling process involves the transfer of the coatings from acarrier ribbon onto a substrate via a combination of heat and pressure.

SUMMARY OF THE INVENTION

[0016] The present invention relates to a method of creating anon-thermally printed medium with a protective overcoat comprising:

[0017] providing a non-thermally printed medium with a printed area;

[0018] applying a protective overcoat over the printed area of themedium by applying heat and pressure to a donor web having a carrierside comprising a carrier material and a transfer side comprising aprotective overcoat material, wherein heat and pressure applied to thetransfer side facilitate release of a section of the transfer side, sothat the section of the transfer side is applied over the printed areaof the medium.

[0019] The present invention also relates to an overcoat for anon-thermally printed medium, the non-thermally printed medium to whichthe overcoat is applied, and the donor web from which the overcoat isapplied to the non-thermally printed medium made by the above-describedmethod.

[0020] The present invention relates to an apparatus comprising:

[0021] a donor web having a carrier side comprising carrier material anda transfer side comprising protective overcoat material,

[0022] a means of applying a protective overcoat a printed area of anon-thermally printed medium, by applying heat and pressure to the donorweb, wherein the heat and pressure facilitate release of a section ofthe transfer side so that the section of the transfer side to is appliedover the printed area of the medium.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a cross sectional view of an overcoated photo qualityprint having a medium (6) having a printable surface on to which an area(4) is printed and a thermal transfer overcoat (2) is also transferredto the printable surface of the medium to cover the printed area.

[0024]FIG. 2 is schematic view of a preferred embodiment of theapparatus of the present invention, showing a frame (8) housing a loader(10), a sheet of the medium (12), a heating element (14), a source roll(16), a take-up roll (18), a tensioned section of the donor web (20) anda base (22).

[0025]FIG. 3 is an alternate schematic view of the apparatus of FIG. 2with the donor web (18) tensioned in a position away from the medium.

[0026]FIG. 4 is a cross sectional view of a preferred embodiment of thedonor web of the present invention.

[0027]FIG. 5 is a cross sectional view of a preferred embodiment ofovercoated print, in which the area of the printable surface with aprinted area is overcoated with a thermal transfer material while thearea of the printable surface without a printed area is not overcoated.

DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention provides a means of creating inexpensive,durable digital prints that can compete or improve upon the quality anddurability of traditional silver halide prints or other coatingprotected digital prints. This invention uses a thermally-transferred,transparent overcoat, which is applied as a colorless transparent film,to protect the printed area on the media.

[0029] The overcoated media of the present invention is obtained bytransferring the thermal transfer overcoat from a donor web which has atop side of carrier ribbon material, the carrier ribbon materialanchoring the bottom side which has at least one layer of overcoatmaterials. The bottom side may include a release layer, a thermaltransfer material, and an adhesive layer. The thermal transfer materialmay be a single layer or include multiple material layers. As the donorweb is heated and pressed into contact with the printable surface of amedium, the thermal transfer overcoat is transferred onto the printablesurface of the medium.

[0030] The clear thermal transfer overcoat of the present inventionimproves print area quality and increases durability of the printedareas. For example, the overcoat provides good protection againstvarious substances that might spill, either in the form of liquid or dryspills, on the surface of a print. Non-limiting examples of substanceswhich the present invention would protect against would be water,alcohol, ink, coffee, soda, ammonia based or other cleaning liquids,food stains (e.g. mustard, chocolate, berry), and dirt.

[0031] The clear, thermal transfer overcoat can be applied in a way thatprovides, for example, a gloss finish or a matte finish. This may beachieved through the control of the application temperature, pressure,and speed. In addition, the creation of patterns using a thermal bar asthe heating element can be used to create unique matte or patternedfinishes.

[0032] The composition of the overcoat can be formulated to targetspecific properties. It can be formulated to achieve a specific gloss ormatte level, and to enhance the gloss uniformity or the matteuniformity. It can also be formulated with materials or additives whichimprove the printed area, specifically, indoor light fade resistance, UVlight fade resistance, resistance to water and other liquids, vaporresistance, scratch resistance and blocking resistance. In a preferredembodiment, the overcoat can also be formulated to have a colorless orcolor-tinted appearance, provide a flexible, conformable coating,decrease the required dry time, optimize the adhesion of the thermaltransfer overcoat to the medium, optimize the release of the thermaltransfer overcoat from the donor web, and minimize the adhesion of thethermal transfer overcoat to the base.

[0033] Within, the thermal transfer overcoat, there can be layers thatenhance the transfer to the printable surface of the medium. Theseadditional layers can include, for example, an adhesive layer positionedas the exterior layer of the thermal transfer overcoat. The primaryfunction of this adhesive layer is to enhance the fixation of thethermal transfer overcoat onto the printable surface of the medium.Another example is a release layer positioned on the interior surface ofthe thermal transfer overcoat next to the interior surface of thecarrier ribbon material. The adhesive layer and the release layer canalso include additives which enhance indoor and UV lightfade resistance,resistance to water and other liquids, vapor resistance, scratchresistance and blocking resistance in the printed areas on the printablesurface.

[0034] Non-limiting examples of light resisting additives that can beadded to the thermal transfer overcoat to be transferred to theprintable surface of the medium in the form of a clear overcoat are thehindered amine series light stabilizers. The hindered amine series lightstabilizer can include commercially available hindered amine serieslight stabilizers having a property of dispersing within a region whichit can react with a dye molecule and deactivate an active species.Preferable specific examples of such hindered amine series lightstabilizers include TINUVIN 292, TINUVIN 123, and TINUVIN 144(trademarks, produced by Japan Ciba-Geigy Company).

[0035] Besides the hindered amine series light stabilizers, the thermaltransfer overcoat can also include UV absorbers, which can include, butare not limited to, the benzophenone series UV absorbers, benzotriazoleseries UV absorbers, acetanilide series UV absorbers, cyanoacrylateseries UV absorbers, and triazine series UV absorbers. Specificpreferred examples are commercially available acetanilide series UVabsorbers such as Sanduvor UVS powder and Sanduvor 3206 Liquid(trademark names, produced by Sando Kabushiki Kaisha); and commerciallyavailable benzotriazole series UV absorbers such as TINUVIN 328, TINUVIN900, TINUVIN 1130, and TINUVIN 384 (trademark names, produced by JapanCiba-Geigy Company), and Sanduvor 3041 Dispersion (trademark name,produced by Sando Kabushiki Kaisha).

[0036] Non-limiting examples of liquid resistance additives or vaporresistance additives that can be added to the thermal transfer overcoat,to be transferred to the printable surface of the medium in the form ofa clear overcoat are additives that decrease the wetability of thesurface by decreasing the surface energy, thereby repelling liquids suchas (but not limited to) water from the surface. These additives mayinclude the family of fluoro-surfactants, silanes, siloxanes,organosiloxanes, siliconizing agents, and waxes or combinations thereof.

[0037] In addition to the use of additives to increase the liquid orvapor resistance, the formulation of the thermal transfer overcoat canprovide improvements. Individual thin layers may develop pits or pinholes in their surface during their coating to the carrier. These holesprovide avenues for liquid or vapor to travel down to the printedsurface. By increasing the number of layers used to create the thermaltransfer material and the total overcoat, the probability of a pinholeextending all the way through the entire layer stack is decreased. Inaddition, this allows the individual layers to be optimized for a uniqueperformance attribute, whereas it may not be possible to acquire aslarge a range of attributes from a single layer. For example, an upperlayer may be optimized for gloss, and it may cover a lower layeroptimized for light fade resistance. The combination of the two may bethe same thickness as a single layer that has lower gloss and inferiorlight fade and liquid resistant properties due to the tradeoffsassociated with formulating that single layer. A single optimizedthermal transfer material layer may be feasible as well.

[0038] One of the layers in the thermal transfer overcoat may consist ofmaterial having barrier properties (i.e., having very low permeabilitytoward gases (e.g., oxygen or water vapor)). Examples of the most widelyused materials with barrier properties are co-polymers of acrylonitrileor co-polymers of vinylidene chloride or vinylidene fluoride. Use ofmaterials with barrier properties in the overcoat makes it possible todramatically increase protection of the overcoated print from humidityand fade (partially caused by oxidation of the colorants.

[0039] The total thermal transfer overcoat should be flexible. Materialsshould be selected such that the final film conforms to the surface ofthe medium. During application, the material should not crack or break,thereby leaving blemishes, area degradations, or exposed medium.Further, the material should conform and adhere to the surface of themedia during bending, flexing, or folding, as might be experiencedduring typical handling.

[0040] The present invention makes possible very thin individual layerson a medium that can be applied either as transparent or opaque layers.Thus, in one embodiment of the invention it is possible to apply thinprotective layers as both undercoating and overcoating to a medium.Providing protective coatings to both media surfaces achieves improveddurability and protection of print qualities without sacrificing goodoptical or media qualities in the finished product.

[0041] The prints of the present invention include a medium material asa substrate for receiving an area. Preferred embodiments of the presentinvention use a completely opaque medium material, but the medium mayalso be transparent. Alternative embodiments use a medium having atransparent or opaque border or frame to provide additional advantagesto the final printed product, such as enhanced aesthetic appeal oradditional structural support (such as by a cardboard frame).

[0042] The medium material can be selected from, for example, but is notlimited to, premium quality photo paper such as HP Premium Photo Paperused for digital color photographic printing or HP Premium HeavyweightPaper used for quality plain paper printing.

[0043] The medium material may also include or be coated with materialswhich increase adhesion of inkjet dyes or pigments, increase adhesion ofthe overcoat material, optimize print quality, increase resistance toscratches, increase resistance to fading, increase resistance tomoisture, or increase resistance to UV light. Such materials include,but are not limited to polyesters, polystyrenes, polystyrene-acrylic,polymethyl methacrylate, polyvinyl acetate, polyolefins,poly(vinylethylene-co-acetate), polyethylene-co-acrylics, amorphouspolypropylene and copolymers and graft copolymers of polypropylene.

[0044] The medium material can also influence the level of gloss, thelevel of matte, the gloss uniformity, or the matte uniformity of theovercoated print. For example, a smooth surface on the medium materialwill facilitate good, voidless adhesion of the overcoat, since the filmis not required to conform to the topography of an uneven or pittedsurface. This will result in a uniformly glossy overcoat surface, onethat has good resistance to moisture and increased light fade resistancedue to the complete sealing of the surface from air or liquids,especially (but not limited to) water-based liquids or their vapors.

[0045] The medium material typically comprises a sheet having first andsecond surfaces in the shape of a square or rectangle, though the shapeof the medium is not limited in any way and the size and thickness ofthe medium may vary. For example, commonly available printer papers maybe used or a medium material of a non-paper material but of the samesize and thickness as commonly available printer papers (e.g., lettersize, legal size, A4, etc.) can be used. Other embodiments may use mediasuitable for use in large-scale imaging applications, such asapplications using the Hewlett-Packard Model 2500 Designjet inkjetprinter typically used in engineering, architecture, or cartographyapplications.

[0046] One of ordinary skill in the art will understand that a printedarea can be applied to a printable surface of the medium material usingcommonly known and available means, such as inkjet or electrostaticprinting. The printing processes of the present invention can include,but are not limited to inks conventionally used in inkjet, offset, andgravure. In addition, it includes the imaging means used in liquidelectrophotography, electrophotography, and conventional photography.When inkjet printing is used, for example, both dye based and pigmentbased inkjets inks can be used, but the invention is not limited to suchinks. These inks, toners, or imaging materials may be formulated tooptimize the adhesion of the thermal transfer overcoat to the printedsurface of the media.

[0047] If inkjet printing is used, excess moisture from the inks mayimpede adhesion or uniform dispersion of the overcoat on the printedsurface.. As long as the media is dry enough for proper adhesion,moisture may dissipate through the overcoat surface over time, since theovercoat is so thin. If excess moisture is trapped between the mediummaterial and the overcoat, the printed area may bloom or blur at itsedges. In a preferred embodiment of the present invention, an optimumcombination of ink, media and thermal transfer overcoat is achievedwhich minimizes excess moisture in the printing process, thus avoidingaccumulations of condensed liquid on the medium. Alternatively, toeliminate such excess moisture, the area may be dried.

[0048] An optional dryer can be used to ensure the ink is dry enough tofacilitate coating adhesion before overcoating. As non-limitingexamples, the dryer can dry the wet printing area using convection,conduction or irradiation (for example, in a preferred embodiment, withany of the following: a radiative heating apparatus, a conductiveheating apparatus, a convective blowing apparatus, an infraredapparatus, an infrared radiative heating element, an ultravioletapparatus and a microwave apparatus). As long as the media is dry enoughfor proper adhesion, excess moisture may dissipate through the overcoatsurface over time, since the overcoat is so thin.

[0049] The printed area may also be preheated prior to coating, tofacilitate the transfer of the overcoat material. If a dryer is used,the drying step may provide this preheating.

[0050] In a preferred embodiment of the present invention, the heatingelement used for transfer is selected from a group consisting of aheated roller, a ceramic heat bar, or a thermal printhead. A heatedroller, similar to what is used in most commercial laminators or manyelectrophotograpic fusers, provides a good means of providing uniform,continuous, full width transfer of the overcoat. A ceramic heat bar,similar to what is used in many monochrome electrophographic fusers(a.k.a. instant-on fusers), also provides a good means of providinguniform, continuous, full width transfer of the overcoat. In addition,ceramic elements have a lower thermal mass than a typical heated roller,thus they quickly reach the desired transfer temperature and quicklycool following transfer, thereby enhancing energy efficiency andreducing start-up time. A thermal printhead, similar to what is used inthermal transfer or dye sublimation printers or faxes, provides a goodmeans of providing continuous or intermittent, full width or discrete,transfer of the overcoat. The heating element can be rigid, or it may becompressible, with the compression level influencing the nip area.

[0051] In another preferred embodiment of the present invention, themedium is positioned over a base, and the heating element and base arepressed towards each other to create a nip area. The base can be rigid,or it can be compressible, with the compression level influencing thenip area. The base may be coated with a non-stick (non-wetting),heat-resistant surface. A solid lubricant can be used to provide thissurface. The solid lubricant may be a fluororesin, fluorocarbon, orfluoropolymer coating such as (poly)-tetrafluoroethylene (PTFE),perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), ethylenetetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE),polyvinylidene fluoride (PVDF), with trade names such as Teflon,Silverstone, Fluoroshield Magna, Cerm-a-lon, Magna TR, Navalon,Apticote, or Edlon. In addition a replenished liquid lubricant, such assilicone oil, can be used to provide this non-stick surface.

[0052] In a preferred embodiment of the present invention, the heatingelement, the base and the donor web span beyond the width of theprintable surface of the medium to be coated. During application, theheating element and base maintain a constant nip force and area acrossthe donor web, which is in contact with the medium. Since the donor weband nip area extend beyond the print sides, full coating to all printedges is insured. The non-stick base surface ensures that the overcoatis only transferred to the printable surface and not to the surroundingnon-stick surface of the base. Only that portion of the thermal transferovercoat that touches the printable surface separates from the donorweb. The rest, including the thermal transfer material overcoat portionextending beyond the edges, remains connected to the donor web. Thepresent design also provides the added feature in that one source ofovercoat can be used to coat any print size narrower than the source,without the need for post process trimming.

[0053] When not being applied, the heating element may be removed fromthe donor web and base surfaces, thereby discontinuing transfer andallowing form feed of the medium under the heater element. Also,application of the coating can be discontinued by reducing thetemperature of the heating element or by reducing the nip force, whichcan be facilitated by raising the heating element or the combination ofthe heating element and donor web off the media surface.

[0054] In addition to limiting the area of transfer of the thermaltransfer overcoat to the printable surface by providing a non-sticksurface on the base under the printable surface, the area of theprintable surface that actually receives a transferred section of thethermal transfer overcoat can be further limited to a specific portionof the printable surface by limiting the section of the thermal transferovercoat to the area in which heat and pressure is applied. This can beaccomplished with the use of a thermal printhead, as used in thermaltransfer printers. For example, selected printed areas, such as colorprinted areas, on the printable surface can be overcoated while otherprinted areas, such as black and white text, can remain uncoated. Suchan embodiment is shown in FIG. 5. Such selective overcoating of discreteareas on media is not feasible with traditional laminates andtraditional laminating processes nor other digital coating processes.

[0055] Also in a preferred embodiment of the present invention, thespeed of the donor web through the heating element is maintained at thesame speed as the medium, thus ensuring a uniform coverage. A sourceroll of donor web is located upstream of the heating element and atake-up roll is located downstream. The source roll is torque limitedwith a slip clutch or similar device to tension and present the thermaltransfer material on the donor web, and to allow the unrolling of thedonor web concurrent with the medium during application but ensuringthat uncontrolled unrolling does not occur. The take-up roll providesenough torque to peel the donor web from the coated medium's surface,but not enough to pull the donor web/medium combination through theapplicator or to distort the coating in the applicator. The take-upmechanism thus peels the donor web from the coated medium, collects thedonor web, and helps maintain the uniform tension on the donor webduring application.

[0056] Assuming the printed area on the medium can be dried quicklyenough through ink and media optimization or post print dryers, athermal transfer overcoat module can be offered to use, for example, asa plug-in module for a printer. An inkjet printer in combination with athermal transfer overcoat module would provide a compact reliable systemfor creating durable photo-quality prints. Alternatively, rather thanhaving the thermal transfer overcoating capability offered as part of aplug-in module which can either be included or not included with theprinter, a printer can be built which completely incorporates thethermal transfer overcoating function into an integrated printing andcoating printer. Alternatively, a stand-alone coater can be used, whichallows the user to hand load the already printed sheets to beovercoated.

[0057] Thermal transfer overcoating is an improvement over lamination aspreviously disclosed. In the present invention a thermal transfermaterial overcoat is transferred onto the medium surface only at thelocations that are subjected to the contact pressure and heat. Thus, itdisengages from the donor web as it transfers and only the thermaltransfer material and not the donor web is attached to the mediumsurface. There is clean separation of the donor web and the mediummaterial at all edges of the print. In contrast, in previously disclosedlaminates, the transferred laminate is still attached to the overcoatsupply source, until separated by a manual or automated trimming step.In the present invention, there is no need for a secondary manual orautomated trimming step to disconnect the thermal overcoat supply source(the donor web) from the overcoated print. This also facilitates theeasy feeding of material and clearing of paper jams.

[0058] In addition, in the present invention, because the thermaltransfer material separates from the donor web at the media's edges, thealignment of film to media is not as critical as alignment of laminateto media. For example, if a laminate is misaligned, excess materialextends beyond the edge of the print, requiring additional postlamination trimming. If a thermal transfer overcoat is misaligned to themedia, the overcoat film of the thermal transfer material stillseparates from the donor web at the edges of the prints and noadditional trimming is required.

[0059] Another advantage of the thermal transfer overcoats of thepresent invention is that the overcoats are thinner than most laminates.Covering the area with a thermal transfer overcoat offers the advantageof providing an intimate, gap-free, bubble free bond with the medium.The differences in the coefficient of thermal expansion between theovercoat and the media will result in less severe curling of thermaltransfer coated prints as compared to laminated ones. In addition, athin film provides a more photo-realistic appearance, whereas typicallaminates provide a plastic or artificial appearance.

[0060] A print of the present invention is illustrated in across-sectional view by FIG. 1. The print comprises medium (6) havingtwo surfaces, a first surface and a second surface. In FIG. 1, the firstsurface is the unprinted side of the medium which may or may not have aprintable surface, while the second surface—to which a printed area isapplied—is the printed side with a printable surface. A printed area (4)is applied to the second surface of the medium (6). A thermal transfermaterial overcoat (2), as disclosed herein, is also applied to thesecond surface of the medium material and at least partly, butpreferably completely, covers the printed area. The printed area can beviewed through the thermal transfer material overcoat. As such, themedium material and thermal transfer material overcoat house and protectthe printed area.

[0061] Prints embodied in the present invention can be produced by avariety of apparatuses. Such apparatuses typically comprise the elementsillustrated in FIG. 2, though it will be appreciated that otherapparatuses may be employed without departing from the scope and truespirit of the present invention.

[0062] The apparatus of FIG. 2 generally comprises a frame (8) housing aloader (10). The loader (10) comprises a mechanism similar to knownmechanisms for loading paper in printers or photocopiers including, butnot limited to, openings for handfeeding individual sheets of media,loading bins capable of holding several sheets of media, or combinationsthereof.

[0063] Once a sheet of the medium material (12) is loaded into thesystem, the take up roll (18), or other similar means, tensions asection (20) of the donor web coming from the source roll (16), and atleast one heating element (14) heats the segment of the donor web andpresses it against the medium (12) positioned on a base (22) (which in apreferred embodiment can be in the form of at least one roller or aplaten) to transfer a segment of the thermal transfer material layer ofthe donor web onto the sheet of the medium material (12) as it movesthrough the system. At the end of the medium (12) the heating element(14) or other similar means, is raised, or the base (22) is lowered, sothat heat or pressure are no longer provided to the donor web. Thethermal transfer overcoat separates from the donor web during transferup to the edges of the medium, with the thermal transfer overcoatadhering to the surface of the medium where the pressure and heat wereapplied and continuing to be attached to the donor web beyond the edgesof the medium.

[0064]FIG. 3 shows the apparatus of FIG. 2 with the ribbon handler (e.g.the take-up roll (18) and source roll (16)) tensioning the donor web ina position away from and no longer abutting the heating element (14) andbase (22). In this position, no thermal transfer overcoat transfers ontoa medium.

[0065] A cross sectional view of a preferred embodiment of the donor webof the present invention is illustrated by FIG. 4. The donor web has acarrier side (11) with lubricant layer (1) and a layer of carrier ribbonmaterial (3) and a transfer side (17) containing the thermal transferovercoat in which the thermal transfer material (7) (which in apreferred embodiment can be a thermoplastic resin, such as an acrylic,polyolefin, polyester and/or their derivatives or combinations thereof)itself is sandwiched between a release layer (5) and an adhesive layer(9). The lubricant layer (1) is on the exterior surface of the carrierside (11). The lubricant layer (1) reduces friction between the donorweb and the heating element The adhesive layer (9) is on the exteriorsurface of the transfer side(17) and helps fix the layers of thetransfer side (17) as an overcoat on the printable surface of themedium. The release layer (5) is on the interior surface of the transferside (17) and promotes the release of the layers of the transfer side(17) from adhering to the carrier side (11) to adhering to the printablesurface of the medium. In one preferred embodiment, the release layer(5) is wax.

[0066]FIG. 5 is a cross sectional view of a preferred embodiment ofovercoated print, in which the area of the printable surface (16) with aprinted area (14) is overcoated with a thermal transfer layer (12) whilethe area of the printable surface (16 ) without a printed area (14) isnot overcoated.

[0067] While the foregoing invention has been described in some detailfor purposes of clarity and understanding, it will be clear to oneskilled in the art from the reading of this disclosure that variouschanges in form and detail can be made without departing from the truescope of the invention.

What is claimed is:
 1. A method of creating a medium with a protectiveovercoat, comprising: applying a protective overcoat to at least onesurface of a medium, by applying heat and pressure to a donor web havinga carrier side comprising carrier ribbon material and a transfer sidecomprising protective overcoat material, wherein the heat and pressurefacilitate release of a section of the transfer side from adhering tothe carrier side of the donor web and facilitate transfer of the sectionof the transfer side to adhering to the at least one surface of themedium.
 2. The method of claim 1, wherein the at least one surface is aprintable surface.
 3. The method of claim 2, wherein the printablesurface comprises at least one printed image.
 4. The method of claim 1wherein heat and pressure are applied to the donor web while the sectionof the transfer side is positioned against the at least one surface ofthe medium and the medium is supported by a base.
 5. The method of claim4, wherein heat is applied to the section of the transfer side by aheating element applied to a section of the carrier side of the donorweb adjacent to the section of the transfer side.
 6. The method of claim5, wherein pressure is applied to the section of the transfer side bycontrolled contact between the heating element applied to the section ofthe carrier side and the base supporting the medium, the donor web andthe medium being sandwiched between the heating element and the base. 7.The method of claim 1, wherein heat is applied to the section of thetransfer side by heat conducted through the base.
 8. The method of claim1, wherein pressure is applied to the section of the transfer side bycontrolled contact between a pressing element applied to a section ofthe carrier side of the donor web adjacent to the section of thetransfer side, the donor web and the medium being sandwiched between thepressing element and the base..
 9. The method of claim 8, wherein thepressing element comprises at least one roller element.
 10. The methodof claim 1, wherein at least a portion of an exterior surface of thebase comprises a surface material resistant to adhering to the sectionof the transfer side.
 11. The method of claim 10, wherein the surfacematerial is selected from the group consisting of a fluororesin coating,a fluorocarbon coating, and a fluoropolymer coating.
 12. The method ofclaim 10, wherein the surface material is selected from the groupconsisting of (poly)-tetrafluoroethylene (PTFE), perfluoroalkoxy (PFA),fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene(ETFE), ethylene chlorotrifluoroethylene (ECTFE), polyvinylidenefluoride (PVDF), their derivatives, and combinations thereof.
 13. Themethod of claim 10, wherein the surface material is silicone oil. 14.The method of claim 1, wherein heat is applied to only a subsection ofthe section of the transfer side, so that only the subsection to whichheat is applied adheres to the at least one surface of the medium. 15.The method of claim 1, wherein pressure is applied to only a subsectionof the section of the transfer side, so that only the subsection towhich pressure is applied adheres to the at least one surface of themedium.
 16. The method of claim 1, wherein the section of the transferside has at least one of a surface width greater than the at least onesurface's surface width and a surface length greater than the at leastone surface's surface length, so that only a subsection of the sectionadheres to the at least one surface, the subsection having a surfacewidth equal to or less than the at least one surface's surface width anda surface length equal to or less than the at least one surface'ssurface length.
 17. The method of claim 1, wherein the base comprises atleast one roller.
 18. The method of claim 1, wherein the base comprisesa platen.
 19. The method of claim 1, wherein the transfer side of thedonor web comprises more than one layer.
 20. The method of claim 19,wherein at least one layer of the transfer side comprises thermoplasticresin material.
 21. The method of claim 20, wherein the thermoplasticresin material is selected from the group consisting of acrylic,polyolefin, polyester, their derivatives, and combinations thereof. 22.The method of claim 19, wherein at least one layer of the transfer sidecomprises a barrier layer resistant to penetration by liquid and air.23. The method of claim 22, wherein the barrier layer comprises apolymeric material selected from the group consisting of polyvinylidenechloride, polyvinylidene fluoride, their derivatives, and combinationsthereof.
 24. The method of claim 1, wherein the carrier side of thedonor web comprises more than one layer.
 25. The method of claim 24,wherein at least one layer of the carrier side is selected from thegroup consisting of thermoplastic resin material and high-densitytissue.
 26. The method of claim 25, wherein the thermoplastic resinmaterial is a polyester.
 27. The method of claim 3, wherein the at leastone printed image is printed by a printing method selected from thegroup consisting of inkjet, offset, gravure, liquid electrophotography,electrophotographic imaging, and conventional photographic imagingmethods.
 28. The method of claim 1, wherein the section of the transferside transferred to adhering to the at least one surface has a surfacefinish selected from the group consisting of matte finish and glossfinish.
 29. The method of claim 1, wherein, when the section of thetransfer side is transferred to adhering to the at least one surface, atleast one textured pattern is stamped onto an exterior surface of thesection.
 30. The method of claim 1, wherein, when the section of thetransfer side is transferred to adhering onto the at least one surface,at least one textured pattern is applied onto an exterior surface of thesection.
 31. The method of claim 1, wherein the section of the transferside transferred to adhering to the at least one surface has improvedfeatures selected from the group consisting of matte uniformity andgloss uniformity.
 32. The method of claim 1, wherein the section of thetransfer side transferred to adhering to the at least one surfaceimproves durability of the at least one surface through addition of atleast one of indoor light fade resistance, ultraviolet light faderesistance, resistance to liquid penetration, resistance to vaporpenetration, scratch resistance, and blocking resistance.
 33. The methodof claim 3, wherein the section of the transfer side transferred toadhering to the at least one surface improves durability and quality ofthe printed image of the at least one surface through addition of atleast one of dry time optimization, optimization of the adhering of thesection of the transfer side to the at least one surface of the mediumand optimization of release of the section of the transfer side fromadhering to the carrier side of the donor web.
 34. The method of claim24, wherein the carrier side of the donor web further comprises alubricant layer as an exterior layer of the carrier side, the lubricantlayer preventing wear of a surface of the heating element coming incontact with carrier side of the donor web.
 35. The method of claim 19,wherein the transfer side of the donor web further comprises a releaselayer as an interior layer of the transfer side adjacent to the carrierside, the release layer facilitating release of the section of thetransfer side from adhering to the carrier side of the donor web. 36.The method of claim 19, wherein the transfer side of the donor webfurther comprises an adhesive layer as an exterior layer of the transferside, the adhesive layer enhancing adhering of the section of thetransfer side to the at least one surface of the medium.
 37. The methodof claim 5, wherein the heating element is selected from the groupconsisting of a heated roller, a ceramic heater element, and thermalprint-head elements.
 38. The method of claim 3, wherein, before the stepof transferring the section of the transfer side to adhering to the atleast one surface of the medium, the method further comprises: dryingthe printed image on the at least one surface of the medium.
 39. Themethod of claim 1, wherein the at least one surface of the mediumfurther comprises a layer that optimizes adhering the section of thetransfer side to the at least one surface of the medium, the adhering tothe at least one surface being strong enough to facilitate release fromthe adhering of the section of the transfer side to the carrier side ofthe donor web.
 40. The method of claim 3, wherein ink used in theprinted image on the at least one surface of the medium optimizesadhering the section of the transfer side to the printed image.
 41. Themethod of claim 1 wherein a protective overcoat is applied to twosurfaces of the medium, the two surfaces being a front surface and areverse surface on a back side of the front surface.
 42. The method ofclaim 38, wherein the drying step is conducted by a method selected fromthe group consisting of convection, conduction and irradiation.
 43. Themethod of claim 38, wherein the drying step is conducted by a dryingelement selected from the group consisting of a radiative heatingapparatus, a conductive heating apparatus, a convective blowingapparatus, an infrared apparatus, an infrared radiative heating element,an ultraviolet apparatus and a microwave apparatus.
 44. A protectiveovercoat for a medium, the protective overcoat made by the method ofclaim
 1. 45. A medium having a protective overcoat made by the method ofclaim
 1. 46. A donor web providing a protective overcoat to a medium,the donor web having: a) a carrier side comprising a carrier ribbonlayer and a lubricant layer as an exterior layer preventing wear of asurface of a heating element or pressing element, the surface coming incontact with the carrier side of the donor web; b) a transfer sidecomprising a protective overcoat material, a release layer as aninterior layer adjacent to the carrier side, the release layerfacilitating release of the transfer side from the carrier side; and anadhesive layer as an exterior layer of the transfer side, the adhesivelayer enhancing adhering of a section of the transfer side to form theprotective overcoat on the medium..
 47. The donor web of claim 46,wherein there is more than one layer of protective overcoat material inthe transfer side
 48. The donor web of claim 47, wherein at least one ofthe layers of protective overcoat material comprises a barrier material.49. An apparatus comprising: a donor web having a carrier sidecomprising carrier ribbon material and a transfer side comprisingprotective overcoat material, a means of applying a protective overcoatto at least one surface of a medium, by applying heat and pressure tothe donor web, wherein the heat and pressure facilitate release of asection of the transfer side from adhering to the carrier side of thedonor web and facilitate transfer of the section of the transfer side toadhering to the at least one surface of the medium.
 50. The apparatus ofclaim 49, wherein the at least one surface is a printable surface. 51.The apparatus of claim 50, wherein the printable surface comprises atleast one printed image.
 52. The apparatus of claim 49 furthercomprising: a means of positioning the section of the transfer sideagainst the at least one surface of the medium, while heat and pressureare applied to the donor web; and a base to support the medium while thesection of the transfer side is being positioned against the at leastone surface of the medium.
 53. The apparatus of claim 49, wherein heatis applied to the section of the transfer side by a heating elementapplied to the carrier side of the donor web.
 54. The apparatus of claim53, wherein pressure is applied to section of the transfer side bycontrolled contact between the heating element and the base, with thedonor web and the medium sandwiched between the heating element and thebase.
 55. The apparatus of claim 49, wherein heat is applied to thesection of the transfer side by heat conducted through the base.
 56. Theapparatus of claim 49, wherein pressure is applied to the section of thetransfer side by controlled contact between a pressing element appliedto a section of the carrier side of the donor web adjacent to thesection of the transfer side, the donor web and the medium beingsandwiched between the pressing element and the base.
 57. The apparatusof claim 56, wherein the pressing element comprises at least one rollerelement.
 58. The apparatus of claim 49, wherein at least a portion of anexterior surface of the base comprises a surface material resistant toadhering to the section of the transfer side.
 59. The apparatus of claim58, wherein the surface material is selected from the group consistingof a fluororesin coating, a fluorocarbon coating, and a fluoropolymercoating.
 60. The apparatus of claim 58, wherein the surface material isselected from the group consisting of (poly)-tetrafluoroethylene (PTFE),perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), ethylenetetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE),polyvinylidene fluoride (PVDF), their derivatives and combinationsthereof.
 61. The apparatus of claim 58, wherein the surface material issilicone oil.
 62. The apparatus of claim 49, wherein heat is applied toonly a subsection of the section of the transfer side, so that only thesubsection to which heat is applied adheres to the at least one surfaceof the medium.
 63. The apparatus of claim 49, wherein pressure isapplied to only a subsection of the section of transfer side, so thatonly the subsection to which the pressure is applied adheres to the atleast one surface of the medium.
 64. The apparatus of claim 49, whereinthe section of the transfer side has at least one of a surface widthgreater than the at least one surface's surface width and a surfacelength greater than the at least one surface's surface length, so thatonly a subsection of the section adheres to the at least one surface,,the subsection having a surface width equal to or less than the at leastone surface's surface width and a surface length equal to or less thanthe at least one surface's surface length.
 65. The apparatus of claim49, wherein the base comprises at least one roller.
 66. The apparatus ofclaim 49, wherein the base comprises a platen.
 67. The apparatus ofclaim 49, wherein the transfer side of the donor web comprises more thanone layer.
 68. The apparatus of claim 49, wherein the at least one layerof the transfer side comprises thermoplastic resin material.
 69. Theapparatus in claim 49, wherein the apparatus further comprises a printercomponent, the printer component applying a printed image to the atleast one surface of the medium before the section of the transfer sideis transferred to adhering to the at least one surface of the medium.70. The apparatus in claim 49, wherein the section of the transfer sideis transferred to adhering to the at least one surface of the medium,the at least one surface having a printed image already applied by aprinter separate from the apparatus.
 71. The apparatus in claim 49,wherein the apparatus is a module installable as a component of aseparate printer.
 72. The apparatus in claim 68, wherein thethermoplastic resin material is selected from the group consisting ofacrylic, polyolefin, polyester, their derivatives and combinationsthereof.
 73. The apparatus of claim 67, wherein at least one layer ofthe transfer side comprises a barrier layer resistant to penetration byliquid and air.
 74. The apparatus of claim 73, wherein the barrier layercomprises a polymeric material selected from the group consisting ofpolyvinylidene chloride, polyvinylidene fluoride, their derivatives andcombinations thereof.
 75. The apparatus of claim 49, wherein the carrierside of the donor web comprises more than one layer.
 76. The apparatusin claim 75, wherein at least one layer of the carrier side is selectedfrom the group consisting of thermoplastic resin material andhigh-density tissue.
 77. The apparatus in claim 76, wherein thethermoplastic resin material is a polyester.
 78. The apparatus in claim51, wherein the at least one printed image is printed by a printingmethod selected from the group consisting of inkjet, offset, gravure,liquid electrophotography, electrophotographic imaging, and conventionalphotographic imaging methods.
 79. The apparatus in claim 49, wherein thesection of the transfer side transferred to adhering to the at least onesurface has a surface finish selected from the group consisting of mattefinish and gloss finish.
 80. The apparatus in claim 49, wherein theapparatus further comprises a means of stamping at least one texturedpattern onto an exterior surface of the section of the transfer sidetransferred to adhering to the at least one surface of the medium. 81.The apparatus in claim 49, wherein the apparatus further comprises ameans of heating and pressing at least one textured pattern onto anexterior surface of the section of the transfer side transferred toadhering to the at least one surface of the medium.
 82. The apparatus ofclaim 49, wherein the section of the transfer side transferred toadhering onto the at least one surface has improved features selectedfrom the group consisting of matte uniformity and gloss uniformity. 83.The apparatus of claim 49, wherein the section of the transfer sidetransferred to adhering to the at least one surface improves durabilityof the at least one surface through addition of at least one of indoorlightfade resistance, ultraviolet light fade resistance, resistance toliquid penetration, resistance to vapor penetration, scratch resistance,and blocking resistance.
 84. The apparatus of claim 51, wherein thesection of the transfer side transferred to adhering to the at least onesurface improves durability and quality of the printed image of the atleast one surface through addition of at least one of dry timeoptimization, optimization of the adhering of the section of thetransfer side to the at least one surface of the medium, andoptimization of release of the section of the transfer side fromadhering to the carrier side of the donor web.
 85. The apparatus ofclaim 75, wherein the carrier side of the donor web further comprises alubricant layer as an exterior layer of the carrier side, the lubricantlayer preventing wear of a surface of the heating element coming incontact with the carrier side of the donor web.
 86. The apparatus ofclaim 67, wherein the transfer side of the donor web further comprises arelease layer as an interior layer of the transfer side adjacent to thecarrier side, the release layer facilitating release of the section ofthe transfer side from adhering to the carrier side of the donor web.87. The apparatus of claim 49, wherein the transfer side of the donorweb further comprises an adhesive layer as an exterior layer of thetransfer side, the adhesive layer enhancing adhering of the section ofthe transfer side to the at least one surface of the medium.
 88. Theapparatus in claim 53, wherein the heating element is selected from thegroup consisting of a heated roller, a ceramic heater element, andthermal print-head heating elements.
 89. The apparatus in claim 51further comprising a drying element, the drying element drying theprinted image on the at least one surface of the medium.
 90. Theapparatus of claim 49, wherein the at least one surface of the mediumfurther comprises a layer that optimizes adhering the section of thetransfer side to the at least one surface of the medium, the adhering tothe at least one surface being strong enough to facilitate release fromthe adhering of the section of the transfer side to the carrier side ofthe donor web.
 91. The apparatus of claim 51, wherein ink used in theprinted image on the at least one surface of the medium optimizesadhering the section of the transfer side to the printed image.
 92. Theapparatus of claim 49 wherein a protective overcoat is applied to twosurfaces of the medium, the two surfaces being a front surface and areverse surface on a back side of the front surface.
 93. The apparatusin claim 89, wherein the drying element is selected from the groupconsisting of a radiative heating apparatus, a conductive heatingapparatus, a convective blowing apparatus, an infrared apparatus, aninfrared radiative heating element, an ultraviolet apparatus and amicrowave apparatus.